The Taiwan Strait, along with the southeastern continental margin of the Eurasian plate, Fujian in SE China, is not far from the convergent boundary between the Eurasian plate and the Philippine Sea plate. Although this region is considered tectonically relatively inactive, many small earthquakes still occur, and normal faults are well developed in the strait. To better understand the geological processes in this region, we use 2 years of ambient noise data from more than 100 stations in Fujian and Taiwan to obtain a 3‐D crustal shear‐wave velocity model using a direct surface‐wave inversion method. Our results show that the low‐velocity zone beneath the Zhenghe‐Dapu suture zone plays an important role in the tectonic evolution of the Fujian area. The relatively high velocity in the eastern part of the suture zone and low velocity in the west correspond to the Mesozoic magmatic zone and the Wuyi‐Yunkai orogenic belt in Fujian, respectively. The coastline of Fujian presents a high‐velocity anomaly in the upper crust, which is related to the Mesozoic Pingtan‐Dongshan metamorphic belt. The long strip‐like high‐velocity zone through the rift basins in the strait is interpreted as igneous rocks due to extension of the lithosphere in the Cenozoic. Two‐stage extension with different extensive centers in the strait may be the reason for the high‐ and low‐velocity anomalies in the middle to lower crust and uppermost mantle of the strait.
The Fujian‐Taiwan Strait‐Taiwan region, as the active eastern margin of Eurasia since the Mesozoic, has experienced the subduction and retreat of the Paleo‐Pacific plate from the Middle Mesozoic, the breakup of the continental margin in the early Cenozoic, and then the collision with the Philippine Sea plate in the late Cenozoic. To better understand the tectonic evolution process, a high‐resolution 3‐D shear wave velocity model of the crust and upper mantle was obtained from surface wave tomography through a direct inversion method. Intermediate‐ to long‐period Rayleigh wave dispersion curves, extracted from teleseismic surface wave with the traditional two‐station method, were combined with the short‐period dispersion curves obtained from ambient noise cross correlation to obtain broader band surface wave data. Two groups of large‐scale low‐velocity bodies are found to be located in the upper mantle of Fujian and the Taiwan Strait and are inferred to be closely related to the magmatic activities caused by the Mesozoic subduction and Cenozoic extension, respectively. The low‐velocity anomalies in Fujian are concentrated in the west Cathaysia block in deep regions and split into small bodies in the uppermost mantle, while the low‐velocity body in the strait is divided into northern and southern parts, corresponding to the two‐stage Cenozoic extension. The velocity gradient was also calculated to estimate the lithospheric thickness, which is only 60–80 km, and the lithosphere‐asthenosphere boundary also features strongly horizontal variations and discontinuities. Our results provide important seismological constraints to investigate the geological and tectonic processes of this region.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.